Big Business, Big Government, and Big Labor — as Examiner colleague Michael Barone put it last week, they’re the Big Units, that often wield their clout to their own benefit and to the detriment of the public.

Often, Big Business and Big Labor have competing interests, thus checking one another’s power. But often they’re on the same side.

In honor of Labor Day, here are some examples of Big Labor colluding with Big Business:

In the 1950s and 1960s, the United Mine Workers teamed up with the biggest coal companies and the federal government in order to crush smaller coal companies.

Wal-Mart and Costco teamed up in 2007 with Big Labor for a minimum wage hike that would hurt smaller retailers.

The SEIU and Wal-Mart similarly teamed up to push the employer mandate in health-care — another government burden that would fall disproportionately on smaller employers.

And often, Big Labor is indistinguishable from Big Business. Check out my take on the United Auto Workers — which holds: net assets of $1.3 billion; the record for the largest independent expenditure on behalf of a candidate in American history, and its own golf course.